Multitap connector block for heavy conductors



juy 7,1970 P. K. KoLr-:Tsos ETAL 3,519,98

MULTITAP CONNECTOR BLOCK FOR HEAVY CONDUCTORS Filed March 20, 1968 2Sheets-Sheet 1 m Z0 'FIC-5 3 317 0 Z528 J9 f5 2 J8 J `2`5` .j4 Q ZZ .fgm f f5 "l ZIA 'n 3 Z-7` Z5 2z P. K. KoLETsos ETAL 3,519,98

MULTITAP CONNECTOR BLOCK FOR HEAVY CONDUCTORS 2 Sheets-Sheet 2 Allllmlf{di} l L lllllT f Z liv July 7; 1970 Filed March zo, 1968 Patented July7, 1970 3,519,981 MULTITAP CONNECTOR BLOCK FOR HEAVY CONDUCTORS Peter K.Koletsos, Chicago, and Chester E. Pierzchala, Wheaton, Ill., assignorsto Reliable Electric Company, Franklin Park, Ill., a corporation ofIllinois Filed Mar. 20, 1968, Ser. No. 714,641 Int. Cl. H01r 7/14 U.S.Cl. 339-242 9 Claims ABSTRACT F THE DISCLOSURE A ring-shaped member hasa plurality of U-shaped slots along its edge, each side wall of eachslot having an undercut shoulder. A bridge type clamping assemblyinterlocks with the shoulders to close the slot and exert a clampingpressure on a cable located in the slot. The clamp assembly can bewithdrawn from the slot by a longitudinal sliding movement. Each clampassembly comprises a bridge member, set screws passing through same, anda saddle engaged by the set screws to exert gripping force on theconductor. The saddle has end pieces received within recesses in the endsurfaces of the bridge member, thus permitting sliding movement of thesaddle with respect to the bridge member.

This invention relates to a floating multitap connector block for use inpower distribution.

In underground distribution of electric power, referred to in the tradeas URD (underground residential distribution), it is necessary toprovide connector means to tap off the service lines to each house. Ithas previously been proposed to make these tapped connections bythreading each conductor into a hole in a connector block and bysecuring it with a set screw. The connector block has a number of holes,one for each conductor. For each polarity there are two main conductors,one for the incoming main, and one for the outgoing main, and one ormore services conductors.

These conductors are all buried insulated conductors disposed generallyhorizontally in the ground, but at the connector point they are lbentupwardly so that they can terminate in a vault or in a pedestal. Thusall conductor ends are vertically disposed and are parallel to eachother and all are cut off at about the same elevation. The ends of eachconductor are stripped of the insulating jacket, and it is the parallelstripped ends that are threaded into the separate parallel holes of theconnector block. The is supported by the conductors, hence the termfloating Due to the stiffness of the conductors, which are from 3%; ofan inch to about 'Vs inch in diameter form the mains, and somewhat lessfor the service conductors, it is very difcult to manipulate theconductors incidents to threading them into the connector block.

According to our invention, instead of providing a block with throughholes, one for each conductor, the block is provided with slots, and aseparate clamp assembly in the form of a removable bridge is providedfor each slot. Thus, each conductor may be laid in its respective slotby lateral movement; then the clamping assembly or bridge is slid intothe slot over the conductor, and the clamping screws tightened up.

A further difficulty encountered in connector blocks of the prior art isthat in the course of repeated war-ming and cooling cycles throughoutthe months, the clamping means tends to loosen up. According to ourinvention, the bridge type construction permits one to build into thedevice a certain amount of resilience, sutcient to overcome the tendencyof the clamp to loosen up due to the expansion and contraction of theconductors which are clamped.

Other objects, features and advantages will become apparent as thedescription proceeds.

With reference now to the drawings in which like reference numeralsdesignate like parts:

FIG. 1 is a vertical section through a power vault showing a preferredembodiment of our invention;

FIG. 2 is a horizontal section taken along line 2-2 of FIG. l;

FIG. 3 is a vertical section taken along line 3 3 of FIG. 2;

FIG. 4 is a side elevation of one of the bridge type clamp assemblies;

FIG. 5 is an end view of FIG. 4;

FIG. 6 is an elevation of the clamping saddle with the bridge shown indotted lines;

FIG. 7 is a section taken along line 7-7 of FIG. 6; and

FIG. 8 is an enlarged fragmentary section along line 8 of FIG. 2.

Referring now to FIG. 1, the reference numeral 10 identifies an `openbottom vault buried in the ground with a cover 11 removably securedthereto substantially flush with the ground surface. Within the vaultare power mains 12 and 13 which are buried at a level lower than thebottom edge of the vault 10 and are bent upwardly so that they aresubstantially parallel to each other, the upper ends being connected bya connector block 14. In the case of a service tap, there will be otherconductors which are not shown in FIG. l, these being omitted forpurpose of clarity. Also, in a given vault there will be two or threesets of conductors and connector blocks, one for each polarity, butthese also are omitted for the purpose of clarity.

Each of the conductors 12 and 13 are insulated conductors havinginsulating jackets 15 which are stripped from the conductor from a pointjust below the connector block 14. In the final assembly, the conductorsand connector block of a given polarity are enclosed in an insulatingclosure of suitable material, such as polyvinyl chloride, port-ions ofwhich overlap the insulating jacket 16 of each conductor, and whichclosure is not shown since it forms no part of the present invention.

As shown in FIGS. l and 2, the connector block comprises a body portion16 which is provided with a plurality of semicylindrical recesses 17 inits edge surfaces. The body portion 16 may be of any suitableconfiguration, such as rectangular, but a ring-shaped or cylindricalconguration as shown in FIG. 2 is preferred for the reason that sixrecesses or slots 17 may be provided with a minimum amount of metal. Foreach recess 17, there is provided a bridge type of clamp assembly 18having laterally projecting side lugs `19 which interlock withundercutshoulders 20 formed in the side walls of the recesses or slots 17.

Each clamp assembly 18, as shown in FIGS. 4 and 5, comprises a bridgemember 21 provided with tapped openings which receive set screws 22.Each assembly also includes a conductor engaging saddles 23which is ofarcuate shape and which underlies the cylindrical inner surface 24 ofthe bridge member 21.

As shown in FIGS. 6 and 7, the arcuate shaped saddle 23 is provided withupwardly extending end pieces 25 which fit into a correspondingly shapedrecess 26 formed in the end surface of the bridge member 21.

The set screws 22 bear against the arcuate shaped saddle 23 and urge thesame into contact with the conductor 12, as shown in FIG. 2. y

In installation of the URD in the first instance, the two bridge typeclamp assemblies 18 which correspond to the conductors 12 and 13 areremoved by a sliding movement from the respective recesses 17; then thevery stift conductors 12 and 13 are manipulated by lateral fiexingmovements so that they can be inserted into their respective recesses.Then each clamp assembly 18 is slid into place in an axial direction,and the two set screws 22 of each clamp assembly are screwed up untilthe saddle 23 engages the conductors very tightly to develop theresilience of the bridge, the clamping pressure being that representedby from 100 to 200 inch-pounds of screw torque where the screw is a halfinch screw having a pitch of .05 inch.

In a practical embodiment of our invention, the bridge member 21consists of a spring tempered material, such as aluminum alloy 6061-T6with an approximate ultimate strength of 38,000 p.s.i. The deflection ofthis bridge, being about 1A inch thick and having a span ofsubstantially 1 inch between the corners of the shoulders 20, issubstantially .003 inch, under 200-inch-pounds of screw torque, Thisdeflection is well within the elastic limit of the material. Thereforethe bridge will follow the thermal expansion or contraction of the wirethroughout many heat cycles without taking a permanent set. Forinstance, in a solid aluminum conductor, the thermal diametral expansionof a half inch conductor is approximately .0015 inch for a 200 F.temperature rise.

The saddle 23 permits the distribution of clamping force over asubstantial area of the conductor surface with the result that thedeformation, if any, of the conductor will be stabilized at a point suchthat any force exerted by the thermal expansion of the cable diameterwill be taken up by a flexing of the bridge rather than by furtherdeformation of the cable. The saddle is thus necessary to thedevelopment of the stressed condition of the bridge 21.

In the embodiment shown, the clamp assembly 18 is two inches long, andthe saddle area is substantially one square inch, the other dimensionsbeing proportionate. The clamp assembly is designed to develop agripping force of several thousand pounds, and the saddle area issufficiently large that the thermal expansion of the cable will be takenup by the resilience of the bridge, as aforesaid.

When it comes time to install one or more service conductors at thevault location, it will be seen that after they are brought into thevault, and cut to length and stripped, that the sripped end of each canbe laid into a recess 17 of the connector block 14 merely by a lateraliiexing movement. In the former type of construction, it was necessaryto loosen each set screw and lift the connector block from the mains,then position the service conductor and lower the same over the strippedends, or else, in the alternative, to buckle the vertical span of theservice conductor so that it can be threaded into the through hole ofthe connector block. Either one of these operations is time consuming;the second is particularly diicult from a manipulative standpoint; andboth are exceedingly difficult to do with hot tool equipment, that is,when the main is hot.

FIG. 2 shows a service conductor 27 tapped into the power main 12, 13.The block 14 will accommodate three more service conductors.

The end pieces 25 and recesses 26 cooperate to prevent the saddle 23from sliding around the conductor; that is, by preventing angulardisplacement the saddle is always maintained in a position Where it isengaged by the set screws 22, thus eliminating the need for aninterlocking swivel connection between the screw ends and the saddle.The clearance 2S between the edge of end piece 25 and the shoulder ofrecess 26 is substantially .O3 inch, the showing of FIGS. 4 and 5 beingexaggerated for illustrative purposes.

To facilitate installation on the job, the clamp assembly 18 is made asa self-contained unit. The ends 29 of end pieces 25 are bent inwardly toprevent separation of the saddle 23 from the bridge member 21, as shownin FIG. 6. This bending operation is performed after the saddle 23` hasbeen assembled with the bridge member 21, the latter being shown indotted lines to show the thickness dimension.

As shown in FIG. 8, a dimple or upset 30 is formed on the bottom surfaceof the body member 16 in the neck portion 31, which is between theshoulders 20. This dimple 30 expands the neck sufiiciently to interferewith the bridge member 21, and prevents it from dropping out of the bodymember 16.

The present design enables us to use extruded parts for the body member16 and the bridge member 21, thus contributing to low manufacturingcost.

Although only a preferred embodiment of our invention is shown anddescribed herein, it will be understood that modifications and changesmay be made in the construction shown without departing from the spiritof our invention.

We claim:

1. A multitap connector block for heavy conductors comprising a bodymember having a plurality of U-shaped slots formed in an edge portion,said slots providing side walls, said side walls having undercutportions providing inwardly facing shoulders, a self contained bridgingclamp assembly comprising a stiffiy resilient arcuate bridge memberhaving a central portion of arcuate cross section and substantiallyuniform thickness and marginal portions in the form of laterallyprojecting lugs interlocking with said shoulders, a tapped openingextending through said bridge member, a screw extending through saidtapped opening, a cable engaging saddle of arcuate cross section engagedby the inner end of said screw and having portions loosely interlockingwith said arcuate bridge member, said self-contained bridging clampassembly being removable from said U-shaped slot by longitudinal slidingmovement.

2. A connector block as claimed in claim 1 in which said body member isring-shaped.

3. A connector block as claimed in claim 1 in which said body member andsaid bridge member are aluminum extrusions.

4. A connector block as claimed in claim 1, said saddle having endpieces overlapping the end surfaces of said bridge member to preventlongitudinal displacement of said saddle with respect to said bridgemember.

5. A connector lblock as claimed in claim 4, said bridge member havingrecessed end surfaces, said end pieces being disposed in said recessesto prevent angular displacement of said saddle with respect to saidbridge member.

6. A connector block as claimed in claim 5 in which said end pieces haveinwardly bent ends to prevent separation of said saddle from said bridgemember during handling.

7. A connector block as claimed in claim 1, in which said arcuate bridgemember is of a resilient material having a stiffness such that thegripping force developed by said bridging clamp assembly is of an orderof magnitude only slightly less than the reactive force developed by thethermal expanion of a conductor gripped by said clamp assembly, and of aresilience sufficient to follow the thermal expansion and contraction ofsaid conductor without taking a permanent set.

8. A connector block as claimed in claim 7, the area of contact betweensaid saddle and said conductor being such that unit pressure betweensaid saddle and said conductor due to said thermal expansion is lessthan that required to deform said conductor.

9. A multitap connector block for heavy conductors comprising a bodymember having a plurality of U-shaped slots formed in an edge portion,said slots providing side walls, said side walls having undercutportions providing inwardly facing shoulders, a bridge member havinglaterally projecting lugs interlocking with said shoulders, a tappedopening extending through said bridge, a screw extending through saidtapped opening, a cable engaging saddle engaged by the inner end of saidscrew, said bridge.

saddle and screw providing a bridging clamp assembly which can beremoved from said U-shaped slot by longitudinal sliding movement, saidundercut portions dening a neck, and a dimple formed in the bottomsurface of said body member and located in said neck to expand thethickness of said neck to prevent said bridge member from dropping outof said slots.

References Cited UNITED STATES PATENTS 6 3,339,174 8/1967 Walter et al339-244 3,426,319 2/1969 Downs et a1. 339-242 FOREIGN PATENTS 103,5503/1938 Australia. 597,067 4/1934 Germany. 370,109 4/ 1932 Great Britain.

MARVIN A. CHAMPION, Primary Examiner 0 J. H. MCGLYNN, Assistant ExaminerU.S. Cl. X.R.

